Driver to drive?

[Phil Allison]

"Chronic Philharmonic"

Similar, but less obvious considerations affect the choice of BJTs and
MOSFETs.

** Which mosfets ?

You must not confuse switching types with laterals.

They have different characteristics,

** Which mosfets ?

You must not confuse switching types with laterals.

and the skilled engineer will exploit them for optimal effect -- sonic
quality, economy, reliability and so on.

** Which mosfets ?

You must not confuse switching types with laterals.

The marketing department will define the requirements for the product
based on the target market, and the engineer will attempt to design a
product that fits within those constraints.

** It don't have to work that idiotic way at all.

In all that I have read here, I have not seen anything that would
consistently make me select MOSFETs over BJTs.

** Which mosfets ?

You must not confuse switching types with laterals.

But I might have a preference based on a *given set* of product
requirements.

** Pigs might fly too.

Wot an posturing old wind bag you are.



...... Phil

 

[Jon Slaughter]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:u2BBk.721$pr6.427@flpi149.ffdc.sbc.com...

Hello Folks,

Looking for a staunch chip to drive transformers in the 30-150kHz range.
The most powerful (and available) one I found is the MIC4451 but it's 1ohm
Rdson. Way too much.

There are bigger ones but they usually have a charge pump and the
efficiency is pretty poor when operated at less than 3A:
http://rocky.digikey.com/weblib/Infineon/Web%20Data/TDA21201prelimDS.pdf

What I need is n/p channel push-pull output (not two n-channels), no
charge pump because the clock sometimes stops, and ideally 100-200mohm
Rdson. External FETs aren't so hot, too much cross conduction. I was
hoping there'd be n/p synchronous buck converters. But nope, all with
charge pumps.

Any ideas?

--

FS---FDD8424H---Dual N & P Channel half-bridge 40V@20A 54mOhm.pdf

 

[Mike Monett]

Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hello Folks,

Looking for a staunch chip to drive transformers in the 30-150kHz range.
The most powerful (and available) one I found is the MIC4451 but it's
1ohm Rdson. Way too much.

There are bigger ones but they usually have a charge pump and the
efficiency is pretty poor when operated at less than 3A:
http://rocky.digikey.com/weblib/Infineon/Web%20Data/TDA21201prelimDS.pdf

What I need is n/p channel push-pull output (not two n-channels), no
charge pump because the clock sometimes stops, and ideally 100-200mohm
Rdson. External FETs aren't so hot, too much cross conduction. I was
hoping there'd be n/p synchronous buck converters. But nope, all with
charge pumps.

Any ideas?

If you had no luck on a driver and wanted to use a charge pump for the
widest choice of output transistors, could you turn the bottom FET on when
the clock stops?

This would keep the charge pump capacitor primed and ready to go on the
first positive clock. The same thing would work for a full h-bridge. It
might take a bit of glue logic to get things started again in the correct
phase but it shouldn't be too difficult.

Regards,

Mike Monett

 

[Chronic Philharmonic]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48D6C6DF.83D3AADF@hotmail.com...

Chronic Philharmonic wrote:

"RichD" wrote

Who do MOSFET sound better than bipolar, as an audio amp output
driver?

A lot of bits have been spilled on this thread so far, but I think it is
the
same question as "Why do tubes sound better than transistors?" or "How
many
angels can dance on the head of a pin?"

First of all, it implies a truth that may not objectively be the case.
But
tubes, BJTs and MOSFETs all have very different characteristics and
engineering trade-offs.

Actually, certain mosfets are not at all unlike triodes.

I almost said that, but decided to leave it because many other physical
and/or electrical parameters are distinctly different, and I figured I'd get
flamed for that.

More to the point is whether you are anti-science and despise negative
feedback.
And / or LIKE your music deliberately distorted as some seem to do.

I think negative feedback is an extremely powerful tool in electronic,
economic, social and natural systems. But people don't seem to understand
it, so they don't trust it.

 

[Trevor Wilson]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:48D6C6DF.83D3AADF@hotmail.com...

Chronic Philharmonic wrote:

"RichD" wrote

Who do MOSFET sound better than bipolar, as an audio amp output
driver?

A lot of bits have been spilled on this thread so far, but I think it is
the
same question as "Why do tubes sound better than transistors?" or "How
many
angels can dance on the head of a pin?"

First of all, it implies a truth that may not objectively be the case.
But
tubes, BJTs and MOSFETs all have very different characteristics and
engineering trade-offs.

Actually, certain mosfets are not at all unlike triodes.

More to the point is whether you are anti-science and despise negative
feedback.

**It matters not whether a person despises NFB or not. NFB is present in
every amplifier known to man. There are, however, a variety of ways that NFB
can be applied.


--
Trevor Wilson
www.rageaudio.com.au

 

[Guy Macon]

mkr5000 wrote:

I have always grounded the shield but to EARTH ground.

I tried that, but the aircraft manufacturer objected to the practice.

Go figure.

--
Guy Macon
<http://www.GuyMacon.com/>

 

[Jim Yanik]

flipper <flipper@fish.net> wrote in
news:gumdd41p32t1ilq4qc7du9a14jmq6c8t49@4ax.com:

On Sun, 21 Sep 2008 15:55:44 +0100, Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



flipper wrote:

Jim Thompson wrote:

can't you admit that religion has
been the cause of most wars and most ills of the world ?

Why would I when it isn't true?

Not most,

'Most" was the claim.

but a fair few nasty ones that could have been easily avoided.

Oh yeah, sure. Everything is "easily avoided." All it takes is the
other ass hole capitulating.


Graham

Islam DEMANDS capitulation.
That is a basic tenet of Islam.

and no converting back,either.

--
Jim Yanik
jyanik
at
kua.net

 

[Bob Eld]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:bgrad4h1cq4hopbqefhlevapoo5pok8cl4@4ax.com...

On Sat, 20 Sep 2008 19:27:46 +0100, Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



John Larkin wrote:

Overall, religion has done more good than harm. And since it's
probably wired into most humans, it's probably impossible to
eliminate.

Wired into us ? I knew it was a con trick by age 8 or therabouts. How I
finally came to that conclusion in a very literal way amuses me to this
day.

Graham

Well, it's not wired into everyone, but the majority of people believe
in some sort of God or some spiritual equivalent. Religion has been,
and remains, one of the most powerful forces in human relations.

Religion has evolved with civilization. Western religions especially
have been instrumental in fostering learning, science, and morality,
all of which have nurtured progress.
cut....
John

Not really, science, learning and progress occurred despite religion and
often in opposition to it. Religion was not instrumental in fostering those
things. In Europe, for over 1000 years the dogmas and power of religion kept
learning and science from occurring. Science, learning and progress occurred
in inverse proportion to the power of the church and only really flowered
when religion became secondary in the lives of people.

Even in modern day America most science occurs separate from religion and in
inverse proportion to depth of particular religious dogma. In other words,
most scientists are not very religious and most religious people are not
scientists or very scientific. Furthermore science can only flourish where
religion is not the dominant force in society and where it's dogmas are not
codified into the laws and regulations.

 

[Arny Krueger]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:48D687BC.1C785316@hotmail.com

Exactly. KRK have a very good name in that respect at the
moment and I think they do actives.

Mackie HR 824 s are almost an industry standard and are active.

Berhinger 2031a are favored by a number of my pickier friends - also
powered.

 

[Arny Krueger]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:48D6886F.B4A1014B@hotmail.com

MooseFET wrote:

isw <i...@witzend.com> wrote:

If you want to go all the way to having feedback from
the speaker, it seems to me that moving the feedback
detection as close to the sound output as practical is
the way to go. Sensing actual cone movement is better
than sensing the driven voice coil's voltage.

Philips did that decades ago with a piezo transducer
IIRC. No idea why it didn't take off other than Philips
aren't exactly reknowned for hi-fi.

Paradigm Servo-15

Basstech 7

Velodyne

etc.

There are three logical ways to do this:

(1) Positional feedback, I've seen it done with a laser
(2) Velocity feedback, can be as simple as sensing the voltage on a second
voice coil
(3) Accelerometer feedback

Of the three, using an accelerometer probably makes the most sense, as
velocity and position can be obtained from acceleration by sucessive
integration. The integration can be effective, even when done in the analog
domain.

 

[Jon Slaughter]

"Jim Thompson" <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote in
message news:25kdd4dpsrdlfei5o67jnda20cavg0i0uo@4ax.com...

On Sun, 21 Sep 2008 17:44:41 -0500, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:


"Jim Thompson" <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote in
message news:rj0dd41q8em6gngm2rg2msvk6i7gusi6mb@4ax.com...

On Sun, 21 Sep 2008 18:11:11 +0100, Mike V <mike@invalid> wrote:

On Sun, 21 Sep 2008 07:30:45 -0700, "Bob Eld" <nsmontassoc@yahoo.com
wrote:


Ultimately, political correctness caused it. Clinton's overzealous
attempt to bring loans to minorities--qualified or not, by way of the
changes he made under the Community Reinvestment Act--demanded that
banks adopt unsound lending practices to meet their statutory lending
quotas. That planted the seed.

Or should we say ACORN?
http://www.ibdeditorials.com/IBDArticles.aspx?id=306544845091102

Interestingly, ACORN, a group lobbying for these inner city loans, was
represented at that time by ... Mr. Barack Obama.

Small world, isn't it?

Grins,
James Arthur

Yeah right! A trillion in bad loan debt by defaulting minorities? It's
all
due to them lousy negras and spics and gooks. That's what we
republicans
say. If the loans were made to white christian folks we wouldn't have
this
problem, Huh? Only the worst kind of racist bigot (read republican)
would
make such an absurd claim that the trillion dollar problem is caused by
loans to minorities, and of course, It's all Clinton's fault! Idiot.


Bob, I ain't American so don't really care about your parties.

But, the analysis in the link looks OK to an outsider. If it's wrong
offer a reasoned argument not a rant. To be honest your rant
completely undermines your case.

The analysis looks OK here because it's the sort of stupid thing Tony
Bliar and Gordon Brown have been doing over here for the last 10
years.

Bob Eld has earned a JERK rating in my NewsProxy filter ;-)



It's the standard liberal tactic. If you can't argue about substance just
call them a racist. Bob's a typical ignorant liberal. (it's funny how
these
guys claim/act as if they are more accepting of other cultures/views/etc
then turn around and do the same shit they are supposedly criticizing.

Bob just gave us a new word of the day! CAN EVERYONE SAY HYPOCRITE!!!



The hypocrite factor is going to be interesting to watch for in the
upcoming election.

(Bob earned the JERK rating in my filters quite a long time ago ;-)

I guess once a jerk always a jerk

 

[Jorden Verwer]

John Larkin wrote:

No. Google "widest bandwidth transistor" or some such.
All that yields is your post.

Okay, sillyness aside, without the quotes it does indeed return some
results. But I couldn't find a definitive answer either way. I do remember
reading about a BJT that had an ft of 500 GHz a couple of years ago, which
was a new record at the time. It's indeed possible that things have changed
since then, although I'd bet that BJTs can't be far behind.

Of course this is all a whole different game than audio, but frankly I think
both BJTs and MOSFETs offer sufficient bandwith in audio applications these
days.

 

[colin]

ive come in on the end of this thread as i havnt looked here for a while
so i havnt seen the OP, but I thought I'd add my 2pence worth..

basically static electricity is just ordinary electricity that doesnt move
as
someone already said, however this isnt particularly helpfull.
also getting it from a battery implies moving so its not static but this
isnt realy
helpfull either lol.

usualy static electricity is noticable when it is quite high voltage,
and is on the surface of an insulator, particularly such as a old crt
screen,
or balloon, hence it is quite dificult to actually move it as such,
wich is why its tended to be called static in this case.

if the surface has a metal coating or is just a
conductive body insulated form earth, then it becoes a plain old capacitor
and just plain old (moveable) electricity but the atrarctive effect is
little diferent.

humans carrying an electric charge is often refered to as static
electricity,
but its not realy static, we usualy pick it up from insulators wich have a
static charge though.

so wether it static or not is probably a insignificant distinction to you,
I expect what you probably need is just plain old ordinary high voltage,
but just very low current,
this can be got from a battery by a flyback type step up converter.

it sounds like you need quite high voltage, 25kv is doable from a small
batery
and if you have an old tv you can see how much that much it atracts baloons,
and especially dust etc to the front of the screen lol.

not to mention you need a surface with a conductive coating or else theres
little way to get the electricity there, ofc like in a tv the conductive
surface can
be on the back side and this causes a static charge to build up on the front
side.

wether 25kv is enough I have no idea, I gues 250kv becomes quite hard
from a small battery as losses+leakage mean you need a bit of power,
not to mention it requires a good thickness of insulation and the air gap
needed is quite large too!
once you get to 1Mv it becomes a bit silly.

I dont know if I'm correct in assuming that if you have a high K insulator
you might get more atractive force.

theres some realy interesting pages on the internet about whats the highest
voltage acehivable
in air, and why its hard to go much above many megavolts.

hope this helps or is of some interest.

Colin =^.^=



"nuny@bid.nes" <Alien8752@gmail.com> wrote in message
news:e4301b4d-1a5b-4834-b167-7595a8d9531b@b2g2000prf.googlegroups.com...

On Sep 20, 2:26 pm, M8R-lfwj...@mailinator.com wrote:
On Sep 20, 11:06 pm, "n...@bid.nes" <Alien8...@gmail.com> wrote:

You are apparently assuming that "static electricity" automatically
means the carpet-shuffling type of sparky stuff, but that's not the
case. Here it means charges that don't go anywhere but whose fields do
work by inducing charges elsewhere.

By the way a question about what you wrote above. Is this static
electricity (used by SRI's robot) still the same kind of static
electricity as what is present in the "carpet-shuffling type of sparky
stuff"? Or is this a different feature of electromagnetism?

Same basic machinery, slightly different way of using it.

The facts that charges exist in complementary pairs in atoms as
positively charged nuclei and negatively charged electrons, and that
electrons are fairly easy to remove from atoms, is what makes it so
easy for us to manipulate electromagnetic forces. To generate fairly
large-value electrostatic fields all we have to do is peel some
electrons away from some atoms and hold them at some distance.

The carpet-shuffling trick involves mechanically rubbing the
electrons off, while batteries use chemistry to separate charges. In
both cases, when the charges go back where they came from, that's
called "current" and when it goes through air we generally call it a
'spark'. Chemical battery voltages run from large fractions of a volt
up to several, maybe a dozen volts while carpet-shuffling can generate
thousands of volts with amazing ease. An extension of the concept, the
Van de Graaf generator, gets up into the millions of volts.

http://en.wikipedia.org/wiki/Van_de_Graaff_generator

Anyway, the robot's feet basically work because the field extending
out from them reach into the atoms of whatever surface is nearby and
stretch the bonds between the nuclei and the electrons of those atoms.
This causes patches of charge opposite to that on the feet to appear
on the surface (that's basically 'electrostatic induction') and as you
no doubt know, opposite charges attract so the feet are attracted to
the surface. Then the voltages connected to the feet are switched off
and the induced charges in the external surface relax back to
neutrality, so the attractive force disappears.

The only real difference between robofeet and the sparky carpet
stuff is that no charges need actually be peeled off any atoms to make
the robofeet work; it's all in the fields.


Mark L. Fergerson

 

[Mike Monett]

mkr5000 <mikerbgr@gmail.com> wrote:

Thanks. Great article.

John, I have a lot of respect for your opinion so you're saying a
hard earth ground for both ends of the shield with no resistor,
right?

If that's the case and it's a long run than why not even more than
2?

Why not ground in the middle also or every x amount of feet?

The telephone system uses a twisted pair and has a similar problem.
The ground for the telephone may be miles away from your own ground,
so there may be large AC and DC voltage differences between them.

If you look at an old 56k dialup modem, you'll find a tiny
transformer at the input. This isolates the telephone system from
the computer by keeping the two grounds separate. DSL and Ethernet
use a similar transformer for the same reason.

The telephone wires are normally not shielded above ground. DSL
modems have a much greater bandwidth than voice, but they use the
same unshielded wires. In most cases, Ethernet cables are not
shielded either. If shielding is not necessary for these systems,
why use it for RS485?

So if you are planning a short run on RS485, you can probably just
use twisted pair. But plan on isolation transformers for longer
runs, or one that goes between buildings than have their own ground
system.

Shielding should not be necessary, unless you have a source of
interference that is in the same frequency band as the RS485 data.

For example, if you have a lot of cables in a long duct that carry
the same type of data, you can get crosstalk that might be strong
enough to cause interference. One solution might be to reroute the
vulnerable lines to keep them away form the source of interference.

If the interference is out of band, such as from the transmitter in
a cell phone, a simple filter at the input of the RS485 receiver
should solve the problem.

So in all these cases, you need to look at the situation and
determine what is actually needed to make it work. One method is to
compare it to other similar systems and find out what they use. If
it works, why make it more complicated?

Best Regards,

Mike Monett

 

[Mike Monett]

mkr5000 <mikerbgr@gmail.com> wrote:

Also, it was asked what type of noise I'm trying to reduce.

Induced crap from lightning strikes or nearby industrial rf
garbage mainly.

You are not going to get much satisfaction from shielding against
nearby lightning strikes. That would take fibre.

Industrial RF garbage may be no concern. For example, does it
interfere with DSL?

It could be in the ISM bands and well above the RS485 data rate. A
simple low pass filter at the receiver should solve that.

So all you have left is the common mode voltages between system
grounds, which can be solved with small isolation transformers.

Best Regards,

Mike Monett

 

[Jon Slaughter]

"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:48D70B12.F31644F5@hovnanian.com...

Jon Slaughter wrote:

"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:48D46820.B9296E2A@hovnanian.com...
Jon Slaughter wrote:

[snip]

My guess is that it makes complete sense but you are just too smart to
understand. Since you believe in giving so much do you accept the 50%
tax
hike on all liberals? Once you guys get your programs going and show
us
that
they are worth it we will then give in.

But the blue states are already net contributors while the red states
are net consumers of federal funds. All that the liberals ask is that
they be able to direct their contributions to those who they believe
deserve them.

You folks just want 50% of the liberals money so you can build bridges
to nowhere.



No, I'd rather have you completely out of the picture. Lets split up into
two countries then.. You and all your buddies can run your side any way
you
want and let us run our side. Then we will see.

We tried that once. Cotton just doesn't pay very well anymore and,
Reconstruction economic policies and all, the south (and in fact most of
the 'red' states today) are net sinkholes for federal tax dollars.

Talk is cheap...

 

[Jon Slaughter]

"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:48D70B12.F31644F5@hovnanian.com...

Jon Slaughter wrote:

"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:48D46820.B9296E2A@hovnanian.com...
Jon Slaughter wrote:

[snip]

My guess is that it makes complete sense but you are just too smart to
understand. Since you believe in giving so much do you accept the 50%
tax
hike on all liberals? Once you guys get your programs going and show
us
that
they are worth it we will then give in.

But the blue states are already net contributors while the red states
are net consumers of federal funds. All that the liberals ask is that
they be able to direct their contributions to those who they believe
deserve them.

You folks just want 50% of the liberals money so you can build bridges
to nowhere.



No, I'd rather have you completely out of the picture. Lets split up into
two countries then.. You and all your buddies can run your side any way
you
want and let us run our side. Then we will see.

We tried that once. Cotton just doesn't pay very well anymore and,
Reconstruction economic policies and all, the south (and in fact most of
the 'red' states today) are net sinkholes for federal tax dollars.

If I recall correctly the north didn't want the south to secede because they
need them economically and not because of slavery(was a minor issue).

So just as hollywood and wallstreet uses mainstreet to live a life of luxury
the north used the south for it's agrocultural strength.

As far as I see it... the "liberals" have been using the good old hard
working boys for centuries so they can live a life free of hard work.

http://liscow.googlepages.com/civil-war-6-07.pdf

So I can see why you wouldn't want such a thing to happen... you would loose
your free lunch. I just wish you'd be honest about it...

 

[Arie]

<boddupalli.ramagopal@gmail.com> wrote in message
news:56328710-5a83-4401-9141-70aefba844a9@c22g2000prc.googlegroups.com...

i work in a direcional drilling company .can we use web camera with
usb port to click the singleshot compass with digital camera kept in
single shot tool and in a monel. and take the reading on to a computer
in surface

There are video transport modules like the Optelecom-NKF 4000 and 4040 that
will do up to 46 km:

http://www.optelecom-nkf.com/optelecom_C01/Modules/ItemBankC/ItemBankC_Item.asp?ComID=1&ModID=19&ItemID=254&SessionID=50274178373780669280101162227#

There are also some modules that transport bidirectional serial data and
contact closure signals together with video:

http://www.optelecom-nkf.com/optelecom_C01/Modules/ItemBankC/ItemBankC_Item.asp?ComID=1&ModID=19&ItemID=255&SessionID=50274178373780669280101162227#


Regards,
Arie de Muynck

 

[Arny Krueger]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:48D7CC74.165531CB@hotmail.com

Arny Krueger wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote

Exactly. KRK have a very good name in that respect at
the moment and I think they do actives.

Mackie HR 824 s are almost an industry standard and are
active.

Berhinger 2031a are favored by a number of my pickier
friends - also powered.

No disrespect to the above two, I'm sure they're quite
competent, but 'serious' studios won't be using them.

Right, they haven't been around for decades and aren't all that costly.

Speaking of reasonably-priced competent but newer monitors, the last two
generations of JBL powered studio monitors are very competent.

KRKs are very popular at the moment with high end studios
for mini-monitors.
http://www.krksys.com/

A friend analyzed a pair and found them to be excessively prone to IM
distortion. Don't remember which model, but any brand that will let stuff
that incompetent out the door deserves a wary look.

 

[Arny Krueger]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:48D7CDE6.D324EB57@hotmail.com

John Larkin wrote:

True, none of this is relevant for audio. Anything will
work for audio.

Well, almost everything. ;-)

Almost anything. RCA's 2N3055s weren't exactly the
fastest in the world. 800kHz fT IIRC.

Sounds about right.

I hate to think
what their germanium predecessors like the OC35 were like.

In the US, their germanium predecessors included the 2N2147s, which were
very fragile. Fried a few myself.

Not only were these germanium audio output devices intrinsically fragile
devices, this was also before SOA protection became common.